Loyally pen about book’s release, first to last (9)

I believe the answer is:

staunchly

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'loyally' is the definition.
(thesaurus)

'pen about book's release first to last' is the wordplay.
I cannot really see how this works, but
'about' could be 'c' (abbreviation for 'circa') and 'c' is located in the answer.
'first' could be 'a' (first letter of the alphabet) and 'a' is located in the answer.
'last' could be 't' (I've seen this in other clues) and 't' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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